JP2012204642A - Surface mounted capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high capacity surface mounted capacitor which easily forms a uniform insulation resin layer for electrically insulating an anode part and a cathode part, prevents short circuits, and has a small leakage current in a capacitor element forming the surface mounted capacitor.SOLUTION: A thickness end surface of a cross section in the shorter side direction of a metal core part 14 of an insulation part 13, formed being covered with an insulation resin layer 15 for electrically insulating an anode part 11 and a cathode part 12, forms shapes protruding in the outer peripheral direction of the metal core part 14.

Description

  The present invention relates to a surface-mounted capacitor that is surface-mounted on a printed wiring board, and more particularly to a surface-mounted capacitor that includes an electrolytic capacitor element that uses a metal as a base material.

  Conventionally, electrolytic capacitor elements (hereinafter referred to as “capacitor elements”) have used a valve metal such as tantalum, aluminum, or niobium as a base material. When aluminum is used, a part of the metal core is enlarged by etching, and a dielectric layer is formed by electrochemical treatment.

  A conventional surface mount capacitor having an anode portion at one end in the longitudinal direction of a capacitor element will be described. FIG. 3 is a diagram showing a capacitor element constituting a conventional surface mount type capacitor. 3A is a plan view, FIG. 3B is an AA cross-sectional view, and FIG. 3C is a BB cross-sectional view.

  The capacitor element 10 constituting the conventional surface mount capacitor shown in FIG. 3 includes a metal core portion 14 as the anode portion 11 and an etching layer 16 in which the surface of the metal core portion 14 as the cathode portion 12 is enlarged. A dielectric layer (not shown) which is an oxide film, a conductive polymer layer 17 which is a solid electrolyte, a graphite layer 18 and a silver paste layer 19 are formed thereon.

  An insulating part 13 made of an insulating resin layer 15 is formed at the boundary between the metal core part 14 and the cathode part 12, which are the anode part 11, so as to cover a part of the anode part 11 by screen printing. A conductive polymer layer 17 is provided on the surface of the dielectric layer formed on the etching layer 16. A cathode layer 12 is formed by sequentially forming a graphite layer 18 and a silver paste layer 19 on the surface of the conductive polymer layer 17. An anode lead (not shown) is connected to the metal core portion 14 of the anode portion 11 of the capacitor element 10 and a cathode lead (not shown) is connected to the silver paste layer 19 of the cathode portion 12, and then molded with an exterior resin. A surface mount capacitor is produced.

  The above-described configuration is disclosed in Patent Document 1, for example. In Patent Document 1, at least a part of the resist resin formed at the boundary between the anode and the cathode is covered with an insulating resin. Thereby, it has the effect of preventing a short circuit due to protrusion of the conductive paste from a predetermined position, or a short circuit due to an element shift at the time of forming a capacitor element laminate.

JP 2009-129936 A

  However, in the conventional technique, as a means for obtaining a surface mount capacitor having a high capacitance in the capacitor element 10 constituting the surface mount capacitor, the surface of the metal core portion is formed on an etching layer having an enlarged surface. The use of a thick aluminum material suitable for increasing the surface area of the dielectric layer to be formed is mentioned. In this case, as shown in FIG. 3C, the aluminum material used for the metal core portion 14 becomes thick, and when the insulating resin layer 15 is formed at the boundary portion between the anode portion 11 and the cathode portion 12 of the capacitor element 10. There is a problem that it is difficult to form the metal core portion 14 uniformly on the side surface portion (the portion surrounded by the dotted line in FIG. 3C).

  In the insulating portion 13 of the capacitor element 10, when the resin amount of the insulating resin layer 15 formed on the side surface portion of the anode portion 11 is insufficient and cannot be sufficiently formed, the conductive polymer layer 17 and the silver paste layer 19 are formed. In this case, it is also formed on the surface of the anode part 11, and a short circuit between the anode part 11 and the cathode part 12 or a leakage current is increased. Further, when the insulating resin layer 15 is formed with a large amount of resin in order to prevent occurrence of short circuit and increase of leakage current, the constituent parts of the anode part 11 and the cathode part 12 become narrow and the effective area decreases. Thus, there is a problem of reducing the capacity of the capacitor element 10.

  Therefore, the surface mount capacitor provided with the capacitor element 10 described above also has a problem that a short circuit occurs and a leakage current is large.

  In the prior art described in Patent Document 1, the number of steps is increased, and when a plurality of capacitor elements are stacked, it is necessary to connect the cathode portion by using a conductive paste for the thickness of the insulating resin. It was.

  In view of this, the present invention provides a surface-mounted capacitor that easily forms a uniform insulating resin layer in order to insulate the anode portion and the cathode portion of the capacitor element, has no short circuit, has a small leakage current, and has a high capacity. The purpose is to provide.

  In order to solve the above-described problems, the present invention provides a metal core portion having a thickness end face in a short-side cross section of a metal core portion of an insulating portion formed by covering with an insulating resin layer to insulate an anode portion and a cathode portion. It is made to have a convex shape in the outer peripheral direction.

  That is, according to the present invention, the oxide film is formed on the anode part formed on at least one of both ends in the longitudinal direction of the metal core part having a rectangular shape, and on the etching layer in which the surface of the metal core part is enlarged. A surface mount capacitor comprising a capacitor element comprising a cathode portion formed so as to cover a dielectric layer, a solid electrolyte, a conductive polymer layer, a graphite layer, and a silver paste layer in order, the metal core portion An insulating part that covers a part of the anode part with an insulating resin layer is formed at the boundary between the metal part and the cathode part, and the thickness end surface of the metal core part forming the insulating part has a thickness end surface of the metal core part. A surface-mounted capacitor having a convex shape in the outer peripheral direction can be obtained.

  Further, according to the present invention, there is obtained the above surface mount capacitor, wherein the convex shape is a stepped shape or a bow shape.

  According to the invention, the insulating resin layer is at least one selected from an epoxy resin, a polyurethane resin, a polyimide resin, a phenol resin, a polyester resin, a polyacrylic resin, and a silicone resin. The above surface mount type capacitor is obtained.

  In addition, according to the present invention, there can be obtained the above surface mount type capacitor, wherein the insulating resin layer is formed by screen printing or pad printing.

  In addition, according to the present invention, there can be obtained the above surface mount type capacitor characterized in that an anode portion is provided at one end in the longitudinal direction of the capacitor element.

  In addition, according to the present invention, there can be obtained the above surface mount type capacitor characterized in that a plurality of the capacitor elements are laminated.

  According to the present invention, since the insulating resin layer can be formed as a uniform layer with few steps with high accuracy, man-hours and costs can be reduced, and the insulating resin layer can be easily manufactured.

  Therefore, since the anode portion and the cathode portion can be reliably insulated by the insulating resin layer, it is possible to provide a high-capacity surface-mount capacitor with less occurrence of short circuit and leakage current.

It is a figure which shows the capacitor | condenser element which comprises the surface mount type capacitor which made the metal core part in the insulating part of this invention stepped. 1A is a plan view, FIG. 1B is an AA cross-sectional view, and FIG. 1C is a BB cross-sectional view. It is a figure which shows the capacitor | condenser element which comprises the surface mount type capacitor which made the metal core part in the insulation part of this invention the bow shape. 2A is a plan view, FIG. 2B is an AA cross-sectional view, and FIG. 2C is a BB cross-sectional view. It is a figure which shows the capacitor | condenser element which comprises the conventional surface mount type capacitor. 3A is a plan view, FIG. 3B is an AA cross-sectional view, and FIG. 3C is a BB cross-sectional view.

  Hereinafter, embodiments of the invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a capacitor element that constitutes a surface-mounted capacitor in which a metal core portion in an insulating portion according to the present invention is stepped. 1A is a plan view, FIG. 1B is an AA cross-sectional view, and FIG. 1C is a BB cross-sectional view.

  As shown in FIG. 1, an insulating portion 13 is formed of an insulating resin layer 15 so as to insulate the anode portion 11 and the cathode portion 12 of the capacitor element 10 constituting the surface mount capacitor. A valve metal such as aluminum, titanium, tantalum, or niobium is used as the base material of the metal core portion 14. Before forming the insulating portion 13, the thickness end surface of the cross section in the short direction of the metal core portion 14 on which the insulating resin layer 15 is formed has a convex shape in the outer peripheral direction such as a step shape or an arc shape in the outer peripheral direction of the metal core portion. is there. In this processing, the thickness end surface of the cross section in the short direction of the metal core portion 14 may be convex in the outer peripheral direction of the metal core portion so that a uniform insulating resin layer can be easily formed. For this formation, a laser forming method is most suitable, but the means is not particularly limited as long as it can be achieved by other methods.

  An anode part is formed at the boundary between the anode part 11 and the cathode part 12 by screen printing or pad printing so that the thickness end face of the cross section in the short direction of the metal core part 14 covers the convex part in the outer peripheral direction of the metal core part. Part of 11 is an epoxy resin to form the insulating resin layer 15. Thereby, as shown in FIG. 1C, the side surface portion is sufficiently covered with the insulating resin layer 15, and the cathode portion 12 can be prevented from coming into contact with the anode portion 11. As the resin of the insulating resin layer 15, an epoxy resin, a polyurethane resin, a polyimide resin, a phenol resin, a polyester resin, a polyacrylic resin, or a silicone resin is selected and used.

  Next, a method for manufacturing the surface mount capacitor of the present invention will be described. The surface of the metal core portion 14 is enlarged by etching or the like, and a voltage is applied by an electrochemical method to form a dielectric layer that is an oxide film on the etching layer 16. After forming the dielectric layer, the portion of the metal core portion 14 where the anode portion 11 is formed is removed by a laser. Next, a conductive polymer layer 17 that is a solid electrolyte is formed on the dielectric layer formed on the etching layer 16 of the cathode portion 12 by chemical polymerization of 3,4 dioxythiophene.

  After forming the conductive polymer layer 17, the graphite layer 18 and the silver paste layer 19 are sequentially formed on the conductive polymer layer 17 to obtain the capacitor element 10. After connecting an anode lead (not shown) to the anode part 11 of this capacitor element 10 and a cathode lead (not shown) to the silver paste layer 19 of the cathode part 12, a surface mount type capacitor is obtained by molding with an exterior resin. Make it.

  In the present embodiment, the description has been given using the example of the capacitor element constituting the surface mount type capacitor having the shape in which the anode part is provided at one end in the longitudinal direction of the capacitor element. It can also be applied to type capacitors. It is obvious that the present invention can also be applied to a surface mount capacitor in which a plurality of the capacitor elements are stacked.

Example 1
The insulating resin layer of the metal core part of the anode part is formed in a shape in which the anode part is provided at one end in the longitudinal direction of the capacitor element shown in FIG. A capacitor element constituting a surface-mounted capacitor having a stepped shape in the outer peripheral direction of the part was produced. The product dimensions of the capacitor element 10 are 6.5 mm (long side) × 3.5 mm (short side) × 0.35 mm (thickness). An aluminum material of 0.4 mm is used for the metal core portion 14, and as shown in FIG. 1C, the thickness end face of the cross section where the insulating resin layer 15 of the metal core portion 14 is formed by the laser is the metal core portion 14. The insulating resin layer 15 of the metal core portion 14 formed in a stepped shape in the outer peripheral direction was formed in a convex shape in the outer peripheral direction of the metal core portion. An insulating resin layer 15 made of an epoxy resin was formed at the boundary between the anode part and the cathode part including the convex part by screen printing to form an insulating part 13.

  Next, the surface of the aluminum material of the metal core portion 14 was expanded by etching or the like, and a chemical treatment was performed by applying a voltage of 6 V by an electrochemical method to form a dielectric layer on the etching layer 16. After forming the dielectric layer, the anode core 11 was removed from the portion of the metal core portion 14 of the anode portion 11 by laser, and the dielectric layer formed on both surfaces of the metal core portion 14 was removed. Thereafter, a conductive polymer layer 17 formed by chemical polymerization of 3,4 dioxythiophene was formed on the dielectric layer formed on the etching layer 16.

  Further, a graphite layer 18 and a silver paste layer 19 were sequentially formed on the conductive polymer layer 17 to form the cathode portion 12 to obtain the capacitor element 10. After connecting an anode lead to the anode body of this capacitor element 10 and a cathode lead to the silver paste layer 19, a surface mount type capacitor was obtained by molding with an exterior resin.

(Example 2)
The insulating resin layer of the metal core part of the anode part is formed in a shape in which the anode part is provided at one end in the longitudinal direction of the capacitor element shown in FIG. A capacitor element constituting a surface-mounted capacitor having a bow shape in the outer peripheral direction of the part was produced. FIG. 2 is a diagram showing a capacitor element constituting a surface mount type capacitor in which the metal core portion in the insulating portion of the present invention has a bow shape. 2A is a plan view, FIG. 2B is an AA cross-sectional view, and FIG. 2C is a BB cross-sectional view. The product dimensions of the capacitor element 10 are 6.5 mm (long side) × 3.5 mm (short side) × 0.35 mm (thickness).

  In Example 2, the thickness end surface of the cross section in the short direction of the metal core part on which the insulating resin layer 15 of the metal core part 14 of the anode part 11 described in Example 1 is formed has a bow shape in the outer peripheral direction of the metal core part. A surface mount capacitor was obtained in the same manner except that it was processed.

(Comparative example)
As a comparative example with Examples 1 and 2 of the present invention, a pair of end surfaces of the cross section in the short direction of the metal core part on which the insulating resin layer of the metal core part of the anode part is formed are straight and not processed A conventional surface mount capacitor shown in FIG. Other manufacturing methods were the same as in Example 1 except that the thickness end face of the cross section in the short direction of the metal core was processed into a straight line to obtain a surface mount capacitor.

  100 surface mount capacitors using the capacitor elements of Examples 1 and 2 of the present invention and 100 surface mount capacitors using the capacitor element of the comparative example, which is a prior art, were manufactured and compared for short-circuit defects. . After applying a voltage of 2.0 V for 60 seconds between the anode lead and cathode lead of each surface mount capacitor, read the current value with an electrometer R8240 (manufactured by Advantest), and a current of 1 mA or more flows. Judged as short-circuited. The results are shown in Table 1.

  From Table 1, it is clear that the short-circuit defect is reduced in the embodiment of the present invention compared to the comparative example, and the effect of the occurrence of the short-circuit and the surface-mounted capacitor with a small leakage current and a high capacity is obtained. I was able to confirm.

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to these embodiments, and the present invention is not limited to the scope of the present invention. Included in the invention. That is, various changes and modifications that can be naturally made by those skilled in the art are also included in the present invention.

  The surface-mount type capacitor according to the present invention can be applied to a solid electrolytic capacitor of a type that is surface-mounted on a printed wiring board of an electronic component or an electric device.

DESCRIPTION OF SYMBOLS 10 Capacitor element 11 Anode part 12 Cathode part 13 Insulating part 14 Metal core part 15 Insulating resin layer 16 Etching layer 17 Conductive polymer layer 18 Graphite layer 19 Silver paste layer

Claims (6)

  An anode formed on at least one of both ends in the longitudinal direction of the metal core having a rectangular shape, a dielectric layer that is an oxide film on the etching layer having the surface of the metal core expanded, and a solid electrolyte A surface-mounted capacitor comprising a capacitor element comprising a cathode portion formed so as to sequentially cover a conductive polymer layer, a graphite layer, and a silver paste layer, wherein the boundary is between the metal core portion and the cathode portion. An insulating part that covers a part of the anode part with an insulating resin layer is formed, and a thickness end surface of a cross section in the short direction of the metal core part forming the insulating part is convex in an outer peripheral direction of the metal core part A surface mount capacitor.   The surface-mount capacitor according to claim 1, wherein the convex shape is a stepped shape or a bow shape.   The insulating resin layer is at least one selected from an epoxy resin, a polyurethane resin, a polyimide resin, a phenol resin, a polyester resin, a polyacryl resin, and a silicone resin. 2. A surface mount capacitor according to 2.   The surface mount capacitor according to any one of claims 1 to 3, wherein the insulating resin layer is formed by screen printing or pad printing.   5. The surface mount capacitor according to claim 1, wherein an anode portion is provided at one end in a longitudinal direction of the metal core portion.   6. The surface mount capacitor according to claim 1, wherein a plurality of the capacitor elements are stacked.

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